Wild germplasm for sweet corn improvement

--I. G. Palacios, R. Burak and J. L. Magoja

With the purpose of enlarging the genetic and germplasm base in sweet corn, the sugary endosperm trait (su) was incorporated into a corn population with diploperennial teosinte introgression (Zea diploperennis) (see MNL 60:82 and 61:65). In order to develop an adequate population in accordance with improvement projects, work is being carried out applying recurrent selection methods to such populations. During the growth season 1989/90 several sweet corn families were tested, among which there were sixty-four full sib families deriving from the introgressed population, being evaluated on the various characters by means of a comparative assay designed as an 8x8 lattice with two replicates.

The results obtained are provided in Table 1 and show that the families are quite precocious, prolific, and expressing low to very high variability according to the character. Those traits concerning the evolutive cycle, height of the plant and number of leaves are of low variation and very closely associated. The tassel branch number, ear insertion height, number of leaves above uppermost ear, ear size, number of kernel rows and kernel per row, are characters with great variation. Lastly, the rest of the characters studied is expressed with high variability, among which, the number of tillers, lodging resistance, prolificity and ear and kernel weight per plant are found.

The heritability values calculated for some of the characters, show the greatest part of the variation is genetic in nature. This leads to the assumption that the population under study may be adequate material to start a project of sweet corn improvement.

Another interesting fact to point out is that, in some of the families, high prolificity is expressed as a consequence of the production of several small ears per plant, which means that an acceptable yield in the production of baby corn would be easier.

Table 1.  Relevant traits and heritability (h2) in full sib families of sweet corn.


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